<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <input type="text">
    <script>
        // let str = 'hello'
        // function demo(str) {
        //     return str.split('').·().join()
        // }
        // demo(str)

        // let arr = [1, 2, 3, 4]

        // function sum(arr) {
        //     return arr.reduce((t, item) => (t += item))
        // }
        // console.log(sum(arr)); //10

        const debounce = (fn, delay = 500) => {
            let timer = null;
            return function() {
                if (timer) {
                    clearTimeout(timer)
                }
                const args = arguments
                timer = setTimeout(() => {
                    fn.apply(this, args)
                }, delay);
            }
        }

        let input = document.querySelector('input')
        input.addEventListener('input', debounce(function(e) {
            console.log(this.value);
        }, 1000))
    </script>
</body>

</html>